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Trace element and isotopic characteristics of Ga-Ge-In bearing vein and breccia systems outboards of Caledonian erosional front
No full textInternational audienc
ForestScan: a unique multiscale dataset of tropical forest structure across 3 continents including terrestrial, UAV and airborne LiDAR and in-situ forest census data
No full textInternational audienceThe ForestScan project was conceived to evaluate new technologies for characterising forest structure and biomass at Forest Biomass Reference Measurement Sites (FBRMS). It is closely aligned with other international initiatives, particularly the Committee on Earth Observation Satellites (CEOS) Working Group on Calibration & Validation (WGCV) AGB cal/val protocols, and is part of GEO-TREES, an international consortium dedicated to establishing a global network of Forest Biomass Reference Measurement Sites (FBRMS) to support EO and encourage investment in relevant field-based observations and science. ForestScan is the first demonstration of what can be achieved more broadly under GEO-TREES, which would significantly expand and enhance the use of EO-derived AGB estimates.We present data from the ForestScan project, a unique multiscale dataset of tropical forest 3D structural measurements, including terrestrial LiDAR scanning (TLS), unmanned aerial vehicle LiDAR scanning (UAV-LS), airborne LiDAR scanning (ALS), and in-situ tree census and ancillary data. These data are critical for the calibration and validation of earth observation (EO) estimates of forest biomass, as well as providing broader insights into tropical forest structure. Data are presented for three FBRMS: FBRMS-01: Paracou, French Guiana; FBRMS-02: Lopé, Gabon; and FBRMS-03: Kabili-Sepilok, Malaysia. Field data for each site include new 3D LiDAR measurements combined with plot tree census and ancillary data, at a multi-hectare scale. Not all data types were collected at all sites, reflecting the practical challenges of field data collection. We also provide detailed data collection protocols and recommendations for TLS, UAV-LS, and plot census measurements for each site, along with requirements for ancillary data to enable integration with ALS data (where possible) and upscaling to EO estimates. We outline the requirements and challenges for field data collection for each data type and discuss the practical considerations for establishing new FBRMS or upgrading existing sites to FBRMS standard, including insights into the associated costs and benefits.</p
Francis Hallé (1938–2025), founder of the study of tree architecture
No full textInternational audienceFrancis Hallé (1938-2025) was one of the most influential French botanists of the last century. He founded plant architectural analysis, showing that post-embryogenic development follows intrinsic, species-specific rules, and that the immense diversity of tree forms can be captured by a finite set of recurring architectural models. He also co-invented the Radeau des Cimes, a canopy-access platform that transformed tropical forest research by making the canopy directly observable and sampleable, and by catalysing ambitious, multinational expeditions. Beyond research, Hallé was an extraordinary communicator: through books, drawings, and public talks, he fought plant blindness and taught generations to look at plants differently. In his final years, he led a major project with the aim to recreate a large, primary forest in Western Europe. Hallé died on 31 December 2025, leaving a scientific, cultural, and ecological legacy that will long outlive him
Uncertainty sources in a large ensemble of hydrological projections: Regional Climate Models and Internal Variability matter
No full textInternational audienceMulti-scenario, multi-model ensembles of hydrological projections are widely used to describe possible futures of regional hydrology and inform adaptation strategies. The Explore2 dataset is such an ensemble of river flow projections in Metropolitan France. It provides future simulations for 1735 catchments with modeling chains composed of different hydrological models forced by 36 regional climate projections based on bias-adjusted EUROCORDEX simulations. This study assesses the uncertainties of this ensemble with QUALYPSO, a method specifically designed to deal with incomplete ensembles and to disentangle and quantify all uncertainty sources, including that due to internal variability. Focusing on results obtained at the end of the century, this study shows a strong agreement between modeling chains towards decreases in low flows in a large southern part of France for a high-emission scenario, and very uncertain changes for the annual mean and high flows. Emission scenario uncertainty is the dominant source of uncertainty for low flows over the whole of France, and for mean annual flows in southeastern France. The contribution of the global and regional climate models is important for mean and high flows, especially in rainfall-dominated areas. Regional climate models contribute considerable uncertainty to low flows, much more than global models. The contribution of hydrological model uncertainty is large for low flows, moderate for mean annual flows, and small for high flows. For all climate and hydrological indicators, internal variability is often large and cannot be overlooked. It is often of the same order and sometimes larger than the uncertainty on the climate change response
Integrative taxonomy resolves a new West African Crocidura (Mammalia: Soricidae) species, cryptic to Crocidura grandiceps in color, but distinct in size
No full textInternational audienceHigh species richness in tropical West Africa has been demonstrated for many species groups, among which shrews are no exception. Within the Crocidura poensis species complex, six species are currently described and recognized in West Africa, but a recent study suggested the existence of an additional cryptic species based on dorsal skull morphology. Here, an integrative approach combining the complete mitochondrial genome, eight nuclear markers, external morphology and geometric morphometrics methods on the skull and mandible of the C. poensis species complex distributed across West Africa is used to test the validity of the new candidate species. Species delimitation analyses performed separately on nuclear and mitochondrial DNA support the existence of seven species. Despite low genetic distance with its closest relative, the new species can be distinguished by several diagnostic nucleotide characters using cytochrome b sequences, by morphometric analyses on the skull and mandible as well as traditional external measurements. This allowed us to describe the new species as Crocidura pediculus Voet, Cornette & Nicolas sp. nov
Fatal Attraction: Light Pollution Creates an Ecological Trap for Wild Fish
No full textInternational audienceEcological traps, poor‐quality habitats that attract animals, significantly threaten ecosystems but have rarely been documented in marine environments. In fish, early life‐history events, such as larval settlement, play a key role in shaping individual survival, population stability, and community interactions. While evidence suggests that late‐stage fish and invertebrate larvae exhibit a phototactic response, the effects of light pollution on larval settlement and survival remain poorly understood. Here, we simulated environmental light pollution on coral reefs using artificial light to examine its impact on fish settlement and post‐settlement consequences. We found that settlement was up to eight times higher onto corals exposed to light pollution compared to those under natural conditions. However, exposure to light pollution reduced recruit survival by half, desynchronized settlement from the full moon and reduced size at settlement. We identified key mechanisms contributing to increased mortality of individuals exposed to artificial light, including disruptions in resting metabolic rhythm and higher predation (due to heightened predator attraction). Additionally, we reveal potential trait compensation in body condition and maximum metabolic rate, traits linked to fitness. However, despite these potential compensatory mechanisms, light pollution functions as a severe ecological trap for fish, attracting individuals into suboptimal environments where they experience higher mortality. This underscores the need to regulate light pollution as a critical environmental stressor
Quand et comment décide-t-on qu’une espèce est éteinte ?
No full textInternational audienceIl est bien plus difficile de prouver une absence que de constater une présence. Il faut donc souvent des années, et un processus minutieux, pour qu’une espèce soit déclarée éteinte. Cela peut-être particulièrement difficile lorsqu’il s’agit d’espèces nocturnes, discrètes ou vivant dans des milieux reculés
Les besoins conflictuels optiques et mécaniques déterminent l'évolution de l'épaisseur de la membrane de l'aile chez les papillons transparents ithomiines
No full textTransparent animals are often thin, which raises the question of their fragility. In clearwing Lepidoptera, the wing thickness is the evolutionary result of conflicting optical and mechanical needs. All else being equal, a thinner membrane lets light better go through, can still sustain the reduced scales it often bears, it has a low stiffness advantageous for flight but it resists less to fatigue and failure, a crucial point. An evolutionary way out of these conflicting needs can be spatial heterogeneity in stiffness, with thicker opaque patches compensating for thinner transparent ones, especially when transparency covers a great wing surface proportion. We tested these predictions in Ithomiine butterflies, a tribe comprising closely-related opaque and transparent unpalatable species. We found that species with partially transparent wings have a thinner membrane in the transparent zone than in the opaque one, which likely helps light getting through and agrees with the lighter weight wings have to support in the transparent zone. Surprisingly, more transparent species have a thicker membrane in their transparent zone. We find no relationship between membrane thickness and scale density, ruling out a predominant role of membrane thickness as a mechanical support for scales. Finally, species with a higher wing proportion occupied by transparency have thicker membranes on their transparent patch, and a greater ratio in thickness between opaque and transparent zones. These latter two results support the hypothesis that clearwing butterflies with larger transparent patches are potentially more fragile and that this frailty is offset by thicker surrounding opaque patches offering higher mechanical resistance, like tubules framing a kite sail. In clearwing butterflies, wing membrane thickness has likely evolved under optical and mechanical selective pressures and further research should experimentally measure the costs, if any, of thinner transparent membranes.Les animaux transparents sont souvent minces, ce qui soulève la question de leur fragilité. Chez les Lépidoptères à ailes transparentes, l’épaisseur de l’aile est le résultat évolutif de besoins optiques et mécaniques contradictoires. Toutes choses égales par ailleurs, une membrane plus fine laisse mieux passer la lumière, et peut pourtant supporter les écailles réduites qu’on trouve souvent dans les zones transparentes. Elle présente une faible rigidité avantageuse pour le vol, mais résiste moins bien mécaniquement à la rupture, un point crucial. Une solution évolutive à ces contraintes opposées peut passer par une hétérogénéité spatiale de la rigidité, avec des zones opaques plus épaisses compensant les zones transparentes plus fines, en particulier lorsque la transparence occupe une grande proportion de la surface alaire.Nous avons testé ces prédictions chez les papillons ithomiines, une tribu comprenant des espèces toxiques étroitement apparentées, à ailes opaques ou transparentes. Nous avons constaté que les espèces partiellement transparentes possèdent une membrane plus fine en zone transparente qu’en zone opaque, ce qui favorise le passage de la lumière et peut quand même soutenir la masse plus faible que les ailes doivent supporter en zone transparente. De manière surprenante, les espèces les plus transparentes présentent une membrane plus épaisse dans leur zone transparente. Nous ne trouvons aucune relation entre l’épaisseur de la membrane et la densité des écailles, ce qui exclut un rôle prédominant de l’épaisseur membranaire comme support mécanique des écailles.Enfin, les espèces dont une plus grande proportion de l’aile est occupée par des zones transparentes présentent des membranes plus épaisses en zone transparente, et un ratio d’épaisseur plus élevé entre les zones opaques et transparentes. Ces deux derniers résultats soutiennent l’hypothèse selon laquelle les papillons à ailes transparentes dotés de larges zones transparentes sont potentiellement plus fragiles, et que cette fragilité est compensée par des zones opaques environnantes plus épaisses, offrant une plus grande résistance mécanique, à la manière de tubulures encadrant la voile d’un cerf-volant. Chez les papillons à ailes transparentes, l’épaisseur de la membrane alaire a probablement évolué sous l’effet de pressions de sélection à la fois optiques et mécaniques, et des recherches futures devraient mesurer expérimentalement les coûts éventuels de membranes transparentes plus fines
Critical metals behavior in amphibolite facies: metamorphic conditions and ore mineral compositions Sulitjelma and Bleikvassli Pb-Zn-Cu mines, Norwegian Caledonides.
No full textInternational audienceAs part of the Critical Metals in Orogen project (https://anr-cmio.gm.umontpellier.fr/), this study focuses on the presence and potential remobilization of critical metals, especially Indium, at the historic Sulitjelma Cu-Zn and Bleikvassli Zn-Pb-Cu mines in the Norwegian Caledonides. The style of mineralization is considered VMS and SEDEX, respectively, but both localities have suffered metamorphism and deformation during the formation of the Caledonian orogen. Ore and host rocks samples of the Sulitjelma and Bleikvassli mines were studied in order to understand the link between metamorphism, mobility, and critical metal concentrations within the mineralizations. To address this issue, several methods were used: macroscopic and microscopic analyses, thermodynamic modelling, EBSD, LA-ICP-MS, LIBS and EPMA in situ analysis. The host rocks are mostly metasediments composed of quartz, micas, garnet, staurolite, kyanite and rare sillimanite. Using pressure-temperature diagrams calculated for the host rock, we obtain for Bleikvassli, temperature conditions between 650 and 750 °C and pressure conditions between 6.5 and 11 kbar. For Sulitjelma, the metamorphic conditions are slightly lower, with temperatures between 550 and 700 °C and pressures between 5 and 12 kbar. These data suggest that the host rocks of the Bleikvassli and Sulitjelma mineralizations experienced amphibolite facies conditions associated with Barrovian metamorphism in a collisional context, in agreement with the available literature. Ore samples are dominated by pyrite–chalcopyrite–sphalerite and pyrrhotite–chalcopyrite–sphalerite assemblages, with the local presence of magnetite. EBSD results show that, in most of the samples, pyrrhotite, pyrite and chalcopyrite show a preferential orientation possibly indicating dynamic recrystallization whereas, sphalerite, appearing texturally late might have crystallized under static conditions. EMPA and LA-ICPMS in situ analytical results on the mineralizations indicate the presence of significant iron in sphalerite in both deposits with 4.4 wt% at Bleikvassli and 5.7 wt% ppm at Sulitjelma. In addition, cadmium, manganese, and indium are preferentially incorporated into sphalerite as well. In both deposits, there is a significant amount of indium in sphalerite, up to 55 ppm. Gallium and germanium concentrations in sphalerite are low. Indium and manganese are also present in chalcopyrite but at lower concentrations. By contrast, tin and silver are preferentially incorporated into chalcopyrite. Cobalt, nickel, and arsenic are enriched in pyrite